GSA HISTORY AND PHILOSOPHY OF GEOLOGY DIVISION GERALD M. AND SUE T. FRIEDMAN DISTINGUISHED SERVICE AWARD: DISCOVERING RELATIONSHIPS BETWEEN VOLCANIC ARCS AND ANCIENT OROGENIC BELTS

Connections between volcanic arcs and mountain systems seemed obvious long ago in such places as southeast Asia-Indonesia and Alaska-Aleutians. It was not everywhere so clear, however, for what of the early-recognized, young, intra-cratonic volcanoes in France, Germany and Eastern Europe. How could these or intra-oceanic volcanic islands bear any relationship to orogenic belts?

Although there were several early 19^th Century descriptions and maps of portions of Asian-margin arcs, the first comprehensive treatment was by Milne in 1886. He showed the coincidence of seismic and volcanic zones in the Circum-Pacific “Ring of Fire” and elsewhere. Slightly later, Eduard Suess compared volcanic island arcs with ancient mountain belts and Alpine geologists interpreted ophiolites as ancient sea floor. In the 1920s-30s, Dutch scientists strengthened Suess’ comparisons of Indonesia volcanoes and trenches with the Alpine-Himalayan belt and Hess did the same for the Caribbean arc. In the late 1930s, Gutenberg and Richter recognized the inclined seismic focal zone as another characteristic of arcs. Then Benioff in 1954 and Kuno in 1959 inferred a causal relationship between specific earthquakes in that focal zone and volcanic eruptions at the surface in Japan. Apparently there were profound movements along that zone.

Meanwhile, as early as the 1840s in Wales and the1890s in eastern USA, ancient volcanic rocks had been recognized within orogenic belts. But these received no further attention until the 1930s when Jones, Stille, Kay, and Eardley documented volcanic zones within several ancient belts - the eugeosynclines of Stille and Kay. These revelations greatly strengthened the connection with arcs suggested by Suess half a century before. At last, after 150 years of speculations about the origin of mountains, by 1970 plate tectonics provided a unified synthesis, which integrated seismology, petrology, structural geology and even stratigraphy.